Control of particle delivery in contamination test rig

Patent metadata

Field	Value
Publication number	US-11566968-B2
Application number	US-202117152436-A
Country	US
Kind code	B2
Filing date	Jan 19, 2021
Priority date	Jan 19, 2021
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

Systems and methods for control of the delivery of contaminates are provided. A conveyor moves contaminate particles from a hopper into an airflow. The contents of a hopper at multiple time points within a sliding window of time are weighted with a scale. A processor applies linear regression to a data set comprising the time points as an independent variable and the weight measurements as a dependent variable, resulting in a determination of a line fitting the data set. A processor determines a current mass flow rate of the contaminate particles from the slope of the line. The processor determines an estimated change in the conveyor motor speed needed to achieve the target mass flow rate, the estimated change determined from a predetermined mapping of flow rates to motor speeds, the estimated change based on the current mass flow rate, the target mass flow rate, and a predetermined fraction.

First claim

What is claimed is:

1. A method of controlling delivery of contaminates, the method comprising:
causing a motor, which drives a conveyor, to rotate at a motor speed,
wherein the conveyor moves a plurality of contaminate particles from a hopper into an airflow, the motor speed corresponding to a target mass flow rate;
weighing contents of the hopper at a plurality of time points within a sliding window of time by taking a plurality of weight measurements with a scale;
applying linear regression, by a processor, to a data set comprising the time points as an independent variable and the weight measurements as a dependent variable, which results in a determination of a line fitting the data set,
determining, by the processor, a current mass flow rate of the contaminate particles from the slope of the line fitting the data set;
determining, by the processor, an estimated change in the motor speed needed to achieve the target mass flow rate, the estimated change determined from a predetermined mapping of flow rates to motor speeds, the estimated change based on the current mass flow rate and the target mass flow rate,
wherein the estimated change is determined to be a fraction of a motor speed adjustment that the predetermined mapping of flow rates to motor speeds indicates from only the current mass flow rate and the target mass flow rate; and
causing, by the processor, a change in the motor speed of the motor in accordance with the estimated change in the motor speed.

2. The method of claim 1 , wherein determining the estimated change in the motor speed further comprises: determining a flow rate error as a difference between the current mass flow rate and a target mass flow rate; calculating a sensitivity slope as a change in motor speed divided by a change in flow rate at the current mass flow rate from the predetermined mapping of flow rates to motor speeds; and calculating the estimated change in the motor speed to be the product of: the sensitivity slope, the flow rate error, and the fraction.

3. The method of claim 1 , wherein determining the estimated change in the motor speed further comprises: determining a first motor speed corresponding to the current mass flow rate from the predetermined mapping; determining a second motor speed corresponding to the target mass flow rate from the predetermined mapping; calculating the indicated motor speed adjustment to be the second motor speed minus the first motor speed; and calculating the estimated change in the motor speed to be the fraction multiplied by the indicated motor speed adjustment.

4. The method of claim 1 , further comprising selecting the motor speed to be a last known speed for the target mass flow rate when starting the motor.

5. The method of claim 1 , further comprising selecting the motor speed corresponding to the target mass flow rate from the predetermined mapping of flow rates to motor speeds when starting the motor.

6. The method of claim 1 , wherein the airflow is in a mix line of a test rig for testing a test valve.

7. The method of claim 1 , further comprising storing the data set comprising the time points and the weight measurements in a FIFO buffer.

8. The method of claim 1 , wherein the fraction is in a range of 0.3 to 0.8.

9. The method of claim 1 , wherein target mass flow rate is in a range of 0.01 to 0.0001 pounds per minute.

10. The method of claim 1 , wherein sliding window of time is a duration in a range of 2 to 4 minutes.

11. A system for controlling delivery of contaminates, the system comprising:
a conveyor configured to feed a plurality of contaminate particles from a hopper towards an airflow, the conveyor including a motor configured to drive the conveyor;
a scale configured to measure the weight of contents of the hopper;
a processor in communication with the motor and the scale, the processor configured to:
cause the motor to rotate at a motor speed corresponding to a target mass flow rate;

receive a plurality of weight measurements from the scale taken within a sliding window of time, each of the weight measurements having a corresponding one of a plurality of time points indicative of when the weight measurements were taken;
apply linear regression to a data set comprising the time points as an independent variable and the weight measurements as a dependent variable, which results in a determination of a line fitting the data set;
determine a current mass flow rate of the contaminate particles from the slope of the line fitting the data set;
determine an estimated change in the motor speed needed to achieve the target mass flow rate, the estimated change determined from a predetermined mapping of flow rates to motor speeds, the estimated change based on the current mass flow rate and the target mass flow rate,
wherein the estimated change is determined to be a fraction of a motor speed adjustment that the predetermined mapping of flow rates to motor speeds indicates from only the current mass flow rate and the target mass flow rate; and
cause a change in the motor speed of the motor in accordance with the estimated change in the motor speed.

12. The system of claim 11 , wherein the processor is configured to determine the estimated change in the motor speed by: determining a flow rate error as a difference between the current mass flow rate and the target mass flow rate; calculating a sensitivity slope as a change in motor speed divided by a change in flow rate at the current mass flow rate from the predetermined mapping of flow rates to motor speeds; and calculating the estimated change in the motor speed to be the sensitivity slope multiplied by the flow rate error multiplied by the fraction.

13. The system of claim 11 , wherein the processor is configured to determine the estimated change in the motor speed by: determining a first motor speed corresponding to the current mass flow rate from the predetermined mapping; determining a second motor speed corresponding to the target mass flow rate from the predetermined mapping; calculating the indicated motor speed adjustment to be the second motor speed minus the first motor speed; calculating the estimated change in the motor speed to be the fraction multiplied by the indicated motor speed adjustment.

14. The system of claim 11 , wherein the processor is configured to set the motor speed to a last known speed for the target mass flow rate in response to a startup of the motor.

15. The system of claim 11 , wherein the processor is configured to set the motor speed to the target mass flow rate from the predetermined mapping of flow rates to motor speeds in response to a startup of the motor.

16. The system of claim 11 , wherein the airflow is in a mix line of a test rig for testing a test valve.

17. The system of claim 11 , wherein the fraction is in a range of 0.4 to 0.7.

18. The system of claim 11 , wherein the target mass flow rate is in a range of 0.01 to 0.0001 pounds per minute.

19. The system of claim 11 , wherein the sliding window of time is a duration in a range of 2 to 4 minutes.

20. A method of controlling delivery of contaminates, the method comprising:
determining a motor speed corresponding to a target mass flow rate from a predetermined mapping of flow rates to motor speeds;
causing a motor, which drives a conveyor, to rotate at the motor speed,
wherein the conveyor feeds contaminate particles from a hopper to an airflow in a mix line of a test rig for testing a test valve;
weighing contents of the hopper at a plurality of time points within

Assignees

• Rolls Royce Corp

Inventors

• Holdmeyer Emily
• Crook Bruce

Classifications

• G05D13/62

  characterised by the use of electric means, e.g. use of a tachometric dynamo, use of a transducer converting an electric value into a displacement {(electric motor control H02P)} · CPC title

• G06F17/17

  Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method ({G06F17/18 takes precedence } ; interpolation for numerical control G05B19/18) · CPC title

• G01M15/02 Primary

  Details or accessories of testing apparatus · CPC title

• G05B13/0245

  not using a perturbation signal · CPC title

• G01N2015/0019

  Means for transferring or separating particles prior to analysis, e.g. hoppers or particle conveyors · CPC title